Mouse models in prion disease are particularly useful as unlike many other neurodegenerative diseases; mice are naturally susceptible to prions and faithfully mirror the clinical and pathological characteristics of the human disease, including the major genetic influence of Prnp. Quantitative trait loci (QTL) mapping studies confirmed the influence of genes other than Prnp in determining incubation time and additional fine mapping and differential expression studies have suggested numerous candidate genes (7–11). Here, PRNP is linked to neurodegenerative disease.